tbuckley/cabot-search huggingface dataset:
EXTH-03. A VEGF+ SUBPOPULATION OF SCHWANN CELLS DRIVES VESTIBULAR SCHWANNOMA TUMORIGENESIS
Authors: David Asuzu, Stefan Stoica, Liyam Laraba, Martin Arhin, Jasleen Gandhi, Dustin Mullaney, Debjani Mandal, David Parkinson, Prashant Chittiboina
Journal: Neuro-Oncology (2023)

Abstract INTRODUCTION Up to 95% of vestibular schwannomas (VS) are sporadic, however their molecular underpinnings remain obscure. OBJECTIVE To perform transcriptomic profiling of VS and investigate novel tumorigenic mechanisms. METHODS We analyzed 19 VS samples (7 sporadic, 12 NF2), and performed single-cell RNA sequencing (scRNAseq, n = 4) or single-nucleus (snRNAseq, n = 15), assays for transposase-accessible chromatin (snATACseq, n = 15) and bulk DNA methylation (n = 14). CellChat was used to predict cell-cell interactions. We characterized transcription factor binding using ChIPseq. We validated our key findings at the mRNA and protein levels using RNAscope (n = 5) and multiplex immunocytochemistry (mIHC; n = 5). Mechanistic studies were conducted using NF2-null Periostin-Cre+ mice versus their Cre- control littermates. RESULTS We profiled the VS transcriptome and identified markers for Schwann cells, macrophages, T cells and endothelial cells. We identified eight Schwann cell subclusters which were enriched for known markers for myelinating, immature, repair and non-myelinating subtypes. We also unexpectedly identified a subset of VS Schwann cells with high expression of VEFGA, and these cells were enriched for signaling via laminin, NCAM, NRXN and NEGR pathways. Using RNAscope and mIHC, we verified VEGFA expression in S100B+ Schwann cells. snRNAseq and snATACseq demonstrated increased TEAD1 expression in Schwann cells, as well as increased chromatin accessibility for TEAD family transcription factor motifs. We used ChIPseq to confirm increased TEAD1 binding at the promoters of 714 genes including VEGFA. NF2-null Periostin-Cre+ mice developed spontaneous schwannomas within their dorsal root ganglia which showed increased vegfa expression, and this was partly reversible using a novel pharmacological TEAD inhibitor in-vivo. CONCLUSIONS We performed detailed epigenetic and transcriptomic profiling of sporadic and NF2-associated VS and uncovered TEAD1-mediated overexpression of VEGFA in a subset of VS Schwann cells. TEAD inhibition may constitute a novel therapeutic target for VS.
BIOM-09. OPPOSING EFFECTS OF LINKED CX3CR1 GERMLINE VARIANTS ON SURVIVAL AND IMMUNE ACTIVATION IN GLIOMA
Authors: Abdul Basit Khan, Malcolm McDonald, Rachel Curry, Yuhui Yang, Latha Khatri, Benjamin Deneen, Akdes Serin-Harmanci, Ganesh Rao
Journal: Neuro-Oncology (2023)

Abstract Linkage-disequilibrium connects CX3CR1 V249I and T280M single-nucleotide polymorphisms; V249I occurs as a single-variant (SV) and T280M exclusively as a double-variant (DV) concurrent with V249I. In low-grade gliomas (LGG), we found improved median overall-survival (mOS) in SV (n = 14, mOS 21.03yrs), compared to WT (n = 45, mOS 9.41yrs) and DV (n = 31, mOS 10.49yrs; p = 0.037 Log-rank). In TCGA glioblastoma (GBM), SV (n = 69, mOS 15.65mo) improved survival over DV (n = 106, mOS 11.74mo; p = 0.044 Log-rank). In a separate GBM cohort, bulk RNA-sequencing revealed MMP9 over-expression in DV (n = 15) compared to SV (n = 10; log2FC 2.87, p-adj 0.079). On a single-gene basis, MMP9 expression was decreased in SV compared to DV and WT (n = 33; p = 0.044, Kruskal-Wallis). MMP9 promotes tumor angiogenesis and invasion. SV showed SPP1 over-expression compared to DV (log2FC -1.75, p-adj 0.026), with decreased SPP1 expression in both WT and DV compared to SV (p = 0.004, Kruskal-Wallis). SPP1 is a pro-inflammatory cytokine enriched in glioma-associated macrophages. Gene Ontology revealed enrichment of biological processes: neutrophil migration, granulocyte chemotaxis, and neutrophil chemotaxis in SV (p&amp;lt; 0.05). We single-cell RNA-sequenced IDH mutant gliomas (51777 cells). We subset and re-clustered myeloid-derived cells (microglia/macrophages, 8944 cells), identifying thirteen clusters. Myeloid-derived cells clustered by CX3CR1 status, with 50.8% of SV cells in cluster five and 85.3% of DV cells in clusters six or seven. Cluster five over-expressed IL1B (average-log2FC 3.23), a tumor-suppressive M1 macrophage marker. Clusters six and seven were characterized by IFIT genes – immunomodulatory in myeloid-derived cells (IFIT3 average-log2FC 2.65 and 2.06). Assessing CX3CR1 status in normal population – 74.2% are WT, 10.0% SV, and 15.7% DV. In glioma patients, we identify 59.9% WT, 14.9% SV, and 25.2% DV – an increase of 49% in SV and 61% in DV (p = 1.95e-6, Chi-square). Our findings demonstrate opposing effects of linked CX3CR1 germline variants on glioma survival and indicate enhanced immune activation in SV.
SURG-16. SAMPLING AND PROCESSING OF TUMOR TISSUE DURING RESECTION OF DIFFUSE INTRACRANIAL GLIOMA: INTERNATIONAL SURVEY AND RECOMMENDATIONS FOR STANDARDIZATION ON BEHALF OF FOUR RANO GROUPS
Authors: Philipp Karschnia, Marion Smits, Guido Reifenberger, Emilie Le Rhun, Benjamin Ellingson, Norbert Galldiks, Michelle M Kim, Jason Huse, Oliver Schnell, Patrick Harter, Malte Mohme, Louisa von Baumgarten, Nathalie Albert, Raymond Y Huang, Minesh Mehta, Martin van den Bent, Michael Weller, Michael A Vogelbaum, Susan Chang, Mitchel Berger, Joerg-Christian Tonn
Journal: Neuro-Oncology (2023)

Abstract BACKGROUND Surgical resection represents the standard of care for newly diagnosed diffuse gliomas and allows neuropathological evaluation for diagnosis. Moreover, tissue specimens form the basis for research allowing the identification of pathogenetic mechanisms and targets. However, there is no consensus which tumor portions should be systematically sampled to achieve a genuinely representative evaluation in a condition characterized by intratumoral heterogeneity. Guidelines for biospecimen handling and long-term storage are also lacking, limiting comparative analyses between different biobanks. METHODS Four international RANO groups from the fields of surgical and medical neuro-oncology, radiation oncology, neuroimaging, and neuropathology aimed to generate a framework for tissue sampling and processing during resection of diffuse glioma. RESULTS A core committee of 21 representatives from the four RANO groups identified areas of interest based upon expert consensus and drafted recommendations for best practice guidelines. Those were eventually sent to 38 leading experts in the field for further evaluation using a two-staged eDelphi process, leading to refinement of the recommendations. Only recommendations which were scored as of ‘critical importance’ by ≥ 70% of the expert panelists were accepted. Consensus recommendations were developed for (I) tissue volume and (neuroimaging-based) tumor-specific regions from where the tumor should be sampled; (II) definitions how regions for sampling of non-contrast-enhancing tumor on MRI should be identified; (III) blood and CSF sampling; (IV) handling and storage to enable both neuropathological diagnosis and in-depth research analyses; and (V) the preferred sample labelling to avoid communication errors. These recommendations resulted in a sophisticated intraoperative workflow proposal to accurately depicture the tumor composition during sampling. CONCLUSION These RANO recommendations offer a framework to standardize the surgical and post-surgical workflow for prospective biobanking studies which will be presented together with the results of the eDelphi survey at the SNO meeting.
STEM-24. WDR5 REPRESENTS A THERAPEUTICALLY EXPLOITABLE TARGET FOR CANCER STEM CELLS IN GLIOBLASTOMA
Authors: Kelly Mitchell, Samuel Sprowls, Sajina Shakya, Sonali Arora, Daniel Silver, Christopher Goins, Lisa Wallace, Gustavo Roversi, Rachel Schafer, Kristen Kay, Tyler Miller, Adam Lauko, John Bassett, Anjali Kashyap, J D'Amato Kass, Erin Mulkearns-Hubert, Sadie Johnson, Joseph Alvarado, Jeremy Rich, Patrick Paddison, Anoop Patel, Shaun Stauffer, Christopher Hubert, Justin Lathia
Journal: Neuro-Oncology (2023)

Abstract Glioblastomas (GBMs) are heterogeneous, treatment-resistant tumors that are driven by populations of cancer stem cells (CSCs). In this study, we perform an epigenetic-focused functional genomics screen in GBM organoids and identify WDR5 as an essential epigenetic regulator in the SOX2-enriched, therapy resistant cancer stem cell niche. Despite their importance for tumor growth, few molecular mechanisms critical for CSC population maintenance have been exploited for therapeutic development. We developed a spatially resolved loss-of-function screen in GBM patient-derived organoids to identify essential epigenetic regulators in the SOX2-enriched, therapy resistant niche. Our niche-specific screens identified WDR5, an H3K4 histone methyltransferase responsible for activating specific gene expression, as indispensable for GBM CSC growth and survival. In GBM CSC models, WDR5 inhibitors blocked WRAD complex assembly and reduced H3K4 trimethylation and expression of genes involved in CSC-relevant oncogenic pathways. H3K4me3 peaks lost with WDR5 inhibitor treatment occurred disproportionally on POU transcription factor motifs, required for stem cell maintenance and including the POU5F1(OCT4)::SOX2 motif. We incorporated a SOX2/OCT4 motif driven GFP reporter system into our CSC cell models and found that WDR5 inhibitor treatment resulted in dose-dependent silencing of stem cell reporter activity. Further, WDR5 inhibitor treatment altered the stem cell state, disrupting CSC in vitro growth and self-renewal as well as in vivo tumor growth. Our results unveiled the role of WDR5 in maintaining the CSC state in GBM and provide a rationale for therapeutic development of WDR5 inhibitors for GBM and other advanced cancers. This conceptual and experimental framework can be applied to many cancers, and can unmask unique microenvironmental biology and rationally designed combination therapies.
RADT-44. LONG-TERM OUTCOMES WITH REDUCED-DOSE WHOLE BRAIN RADIOTHERAPY AND A STEREOTACTIC RADIOSURGERY BOOST FOR PRIMARY CNS LYMPHOMA
Authors: Bronwen Foreman, Trey Mullikin, Scott Floyd, Chris Kelsey, Mallika Patel, Katherine Peters, John Kirkpatrick, Zachary Reitman, Eugene Vaios
Journal: Neuro-Oncology (2023)

Abstract BACKGROUND Primary central nervous system lymphoma (PCNSL) is an aggressive diffuse large B-cell lymphoma. Treatment approaches are historically associated with neurotoxicity, particularly with high-dose whole-brain radiotherapy (WBRT). We hypothesized that reduced dose-WBRT (rd-WBRT) followed by a stereotactic radiosurgery (SRS) boost could provide durable disease control without significant adverse effects. METHODS We retrospectively reviewed PCNSL patients treated with rd-WBRT plus an SRS boost at Duke University between 2008 and 2021. Progression-free survival (PFS) and overall survival (OS) were estimated using competing risk and Kaplan Meier methods. RESULTS We identified 23 patients with pathologically confirmed PCNSL. Median age at diagnosis was 69 years (Q1Q3:52–74) and median KPS was 80 (Q1Q3:70–80). Median follow-up was 21 months. Median doses for rd-WBRT and SRS were 23.4Gy (Q1Q3:23.4–23.4) and 12Gy (Q1Q3:12–12.5), respectively. The cumulative incidence of intracranial progression at two years was 23% (95%CI:8-42). Six patients (26%) developed distant radiographic progression while two patients (9%) developed both distant and local progression. Ten patients (44%) were alive without progression at last follow-up. By Kaplan Meier estimate, the two-year overall survival was 69% (95%CI:46-84). There were no reported grade 3+ radiation-induced toxicities. CONCLUSIONS The combination of rd-WBRT with an SRS boost appears well-tolerated with durable intracranial control. This approach represents a treatment option for select patients, such as those with progressive or refractory disease. Further prospective studies are needed to validate these findings and determine whether this approach could be incorporated into consolidation strategies.
CTNI-54. A COMBINED ANALYSIS OF TWO RANDOMISED STUDIES EXPLORING THE IMPACT OF EXTENDED POST-RADIATION TEMOZOLOMIDE ON SURVIVAL OUTCOMES IN NEWLY DIAGNOSED GLIOBLASTOMA
Authors: Lucy Gately, Carlos Mesia, Juan Sepúlveda, Sonia del Barco, Estela Pineda, Regina Gironés, José Fuster, Wei Hong, Sanjeev Gill, Luis Miguel Navarro, Ana Herrero, Anthony Dowling, Ramón De La Peñas, Maria Angeles Vaz, Miriam Alonso, Zarnie Lwin, Rosemary Harrup, Sergio Peralta, Anne Long, Pedro Perez-Segura, Elizabeth Ahern, Clara Olier Garate, Mark Wong, Robert Campbell, Katharine Cuff, Ross Jennens, Oscar Gallego, Craig Underhill, María Martinez-García, Marta Covela, Adam Cooper, Stephen Brown, Mark Rosenthal, Javier Torres, Ian M Collins, Peter Gibbs, Carmen Balana
Journal: Neuro-Oncology (2023)

Abstract BACKGROUND The optimal duration of post-radiation temozolomide in newly diagnosed glioblastoma remains unclear, with no published phase III randomised trials. Stupp protocol uses 6 months, however, in routine care, it is often extended to 12 months, given its tolerability, lack of effective salvage treatments, and extended regimen in lower grade gliomas. METHODS GEINO14-01 (Spain) and EX-TEM (Australia) studies enrolled patients with newly diagnosed glioblastoma without progression at the end of 6 months post-radiation temozolomide. Participants were randomised in a 1:1 allocation to either six additional months (total 12 months) or observation. Primary endpoint was 6-month progression free survival from date of randomisation (6mPFS). Secondary endpoints included overall survival (OS) and toxicity. 204 patients were required for 80% power to detect an improvement in 6mPFS from 50% to 60%. Neither study recruited sufficient patients, so we performed a combined analysis of individual patient data. RESULTS 205 patients were recruited: 169 in GEINO14-01 (2014–2018) and 46 in EX-TEM (2019–2022). Median follow up was 20 and 14.5 months respectively. Baseline characteristics were balanced. There was no significant improvement in 6mPFS (57.2% vs 64.0%, OR 0.75, p = 0.4), nor across any subgroups including MGMT methylated. There was no significant improvement in PFS (HR 0.92, P = 0.59, median 7.8 vs 9.7 months) or OS (HR 1.03, p = 0.87, median 20.1 vs 19.4 months). During treatment extension, 64% experienced any adverse event, mainly fatigue and gastrointestinal (both 54%). Only a minority required changes to treatment, with 4.5% requiring dose delay, 7.5% dose reduction and 1.5% discontinuation of temozolomide. CONCLUSION For patients with newly diagnosed glioblastoma, extending post-radiation temozolomide from 6 to 12 months is well tolerated but does not improve 6mPFS. We could not identify any individual patient subset that appeared to benefit from extended treatment. Six months should remain standard of care.
TMIC-13. EXHAUSTED CD8+ T CELLS MAINTAIN LOW-GRADE GLIOMAS IN NF1-MUTANT MICE
Authors: Rasha Barakat, Jit Chatterjee, Rui Mu, Xuanhe Qi, Olivia Cobb, Karen Gao, Xingxing Gu, Igor Smirnov, Jonathan Kipnis, David Gutmann
Journal: Neuro-Oncology (2023)

Abstract T cells are minor cellular constituents of the brain tumor microenvironment, but have recently been shown to play critical roles in glioma pathobiology and treatment. Previous studies from our laboratory have shown that T cells are required for the formation and growth of low-grade gliomas (LGGs) in murine models of the Neurofibromatosis type 1 (NF1) tumor predisposition syndrome. To better characterize the immune landscape of these pediatric low-grade tumors, we leveraged single cell RNA sequencing of human pediatric pilocytic astrocytomas and genetically engineered mouse LGG (Nf1-optic glioma) models. First, we showed that both human and murine LGGs contain a CD8+ T cell population expressing PD-1 and TIGIT, similar to conventional exhausted T cell populations. Second, these PD-1+/TIGIT+ CD8+ T cells are actively recruited to the tumor site by Ccl2 where they dictate tumorigenesis through the elaboration of Ccl4, a cytokine necessary for microglia Ccl5-mediated support of Nf1-OPG growth. As such, Ccl4 expression was enriched in PD-1+/TIGIT+ CD8+ T cells relative to all other T cell populations within these tumors. Third, this “exhausted” CD8+ T cell population was exclusively present in the optic nerves, but not in the blood, dura, or deep cervical nodes of optic glioma-bearing mice. Fourth, targeting this PD1+/TIGIT+ exhausted CD8+ T cell population with immune checkpoint monoclonal antibody inhibitors reduced CD8+ T cell tumoral recruitment, Ccl4 production, and optic glioma growth. Collectively, these findings establish an obligate role for PD-1+/TIGIT+ CD8+ T cells in Nf1-optic glioma control and suggest that immune checkpoint modulation may be useful for the treatment of LGGs in children.
DISP-16. RACIAL/ETHNIC DIFFERENCES OF PEDIATRIC BRAIN TUMORS IN PATIENT DERIVED ORTHOTOPIC XENOGRAFT (PDOX) MODEL DEVELOPMENT AND DRUG RESPONSES DETECTED BY HIGH-THROUGHPUT DRUG SCREENING
Authors: Aalaa Abdallah, Yuchen Du, Xiao-Nan Li, Lin Qi, Mari Kogiso, Frank Braun
Journal: Neuro-Oncology (2023)

Abstract Brain tumors are the leading cause of cancer-related death in children. While the last decade has ushered in significant advances in molecular subtyping of pediatric brain tumors, little is known about the biological differences among racial/ethnic populations. We previously completed high-throughput Screening (HTS) in 12 malignant glioma and 13 medulloblastoma models. For each model, cultured xenograft cells (primary or cell line) were maintained both as a classic monolayer and as 3D neurospheres then treated for 3-7 days with a library of ~8,000 drugs/investigational agents, each at 4 different doses (0.01~ 10 µM). The antitumor activities were evaluated by the level of suppressed cell proliferation that was determined by the area under the curve (AUC) for which our cutoff value was set at 0.75. In the current study, we performed a retrospective analysis to determine the race/ethnicity of these completed PDOX models. Our cohort of medulloblastoma models included 3 models from children who self-identified as Hispanic and 5 models from children who self-identified as, that allowed for a statistical analysis (t-test) to compare the differences between these two racial/ethnic groups. From the 8,000 drugs, we identified 11 drugs (mostly NSC compounds) that were equally active in both Hispanic and White children (i.e. commonly shared drugs), and 442 drugs that showed significantly different (P&amp;lt; 0.05) activities between the Hispanic and the White medulloblastomas grown as neurospheres and treated for 7 days. The difference of active drugs (AUC &amp;gt;0.75) was even more prominent. Compared with 38 active drugs in White children (i.e., privately active drugs, including Bortezomib, YM155, Carfilzomib, Daporinad, GMX-1778, Dalanzomib, Cucurbitacin, Bafilomycin, Vincristin and Mitoxantrone), the number was 0 for Hispanic children. Our data indicates a significant difference in drug response across different racial/ethnic groups and provides a strong rationale for additional examination of those differences with broader coverage of tumors.
TMIC-76. GLIOBLASTOMA VESSEL CO-OPTION OCCURS AS A RESISTANCE MECHANISM TO CHEMORADIATION VIA INDUCTION OF A NOVEL CELL STATE
Authors: Aafrin M Pettiwala, Cathy Pichol-Thievend, Oceane Anezo, Guillaume Bourmeau, Remi Montagne, Anne-Marie Lyne, Pierre-Olivier Guichet Guichet, Pauline Deshors, Alberto Ballestin, Benjamin Blanchard, Vidhya M Ravi, Kevin Joseph, Dieter Henrik Heiland, Boris Julien, Sophie Leboucher, Laetitia Besse, Patricia Legoix, Charita Furumaya, Laura Kovandzic Marcos, Konstantin Masliantsev, Thomas Daubon, Oliver Schnell, Jürgen Beck, Nicolas Servant, Lucie Karayan-Tapon, Florence Cavalli, Giorgio Seano
Journal: Neuro-Oncology (2023)

Abstract Glioblastoma (GB) is one of the deadliest types of human cancer. Despite a very aggressive treatment regime-including resection, chemo-radiation, its recurrence rate is more than 90%. Recurrence is mostly caused by highly resistant and invasive cells that spread from tumor bulk and are not removed by resection. To develop an effective therapeutic approach, we need to better understand underlying molecular and cellular mechanism driving therapy resistance and invasion in GB. To dynamically track the changes post-therapy and chemoradiation-resistant cells, we employed multiple bulk and single cell transcriptomics, phosphoproteome, in vitro and in vivo real time imaging, organotypic cultures, functional analysis, digital pathology and spatial transcriptomics on patient material and preclinical models of GB. We demonstrated that the chemoradiation and brain vasculature induce a transition to invasive functional cell state, which we rename as VC-Resist. Better cell survival, G2M arrest, senescence/stemness pathway induction, makes this GB state much more resistant. Notably, these GB cells are highly vessel co-opting allowing homing to perivascular niche, which in turn increases their transition to this cell state. Molecularly, the transition to VC-Resist cell state takes place through FGF-FGFR1 signaling that leads to activation of DNA damage repair, YAP and Rho pathways. These findings demonstrate that the perivascular niche and GB cell plasticity jointly generates a vicious loop that leads to resistance and brain infiltration during GB recurrence.
RADT-07. CLINICAL OUTCOMES OF MELANOMA BRAIN METASTASES TREATED WITH NIVOLUMAB AND IPILIMUMAB ALONE VERSUS NIVOLUMAB AND IPILIMUMAB WITH STEREOTACTIC RADIOSURGERY
Authors: Joseph Tang, Matthew Mills, Ammoren Dohm, Nikhil Khushalani, Peter Forsyth, Michael A Vogelbaum, Evan Wuthrick, Hsiang-Hsuan Michael Yu, Daniel Oliver, James Liu, Kamran Ahmed
Journal: Neuro-Oncology (2023)

Abstract BACKGROUND Upfront dual checkpoint blockade has demonstrated efficacy in new melanoma brain metastases (MBM) of asymptomatic patients. Whether combination stereotactic radiosurgery (SRS) with dual checkpoint blockade improves outcomes over dual checkpoint blockade alone is unknown. We evaluated clinical outcomes of new MBM receiving nivolumab and ipilimumab, with and without SRS. METHODS 52 patients with 171 MBM receiving nivolumab and ipilimumab for untreated MBM between 2015 and 2022 were identified at our institution. Patient and tumor characteristics including age, Karnofsky Performance Status (KPS), presence of symptoms, cancer history, MBM burden, and toleration of therapy were recorded. Outcomes measured from initiation of MBM-directed therapy included overall survival (OS), local control (LC), distant intracranial control (DIC), and intracranial control (ICC). Time-to-event analysis was conducted with the Kaplan-Meier method. RESULTS 25 patients with 74 MBM received nivolumab and ipilimumab alone. 27 patients with 97 MBM received concurrent SRS. No differences in age (p = 0.72), KPS (p = 0.94), presence of symptoms (p = 0.87), prior MBM (p = 0.90), prior MBM-directed surgery (p = 0.77) or SRS (p = 0.65), MBM size (p = 0.36), MBM number (p = 0.36), or treatment completion (p = 0.12) were seen. Median follow-up was 22.7 months. There was a trend towards higher rates of nivolumab and ipilimumab course completion in the combination group (44% vs. 24%; p = 0.12). The combination therapy group received prior immunotherapy more often than the monotherapy group (52% vs. 8.0%; p = 0.0003). OS, DIC, and ICC were similar (p = 0.16, p = 0.32, p = 0.57, respectively) with overall 12-month OS 70.7%, DIC 56.8%, and ICC 49.4%. The combination therapy group had higher 12-month LC compared to the monotherapy group (91% vs. 64%; p = 0.001). CONCLUSION In our analysis, SRS with nivolumab and ipilimumab shows superior LC compared to nivolumab and ipilimumab alone despite our combination cohort being more advanced with higher rates of prior immunotherapy. Further prospective study of combination nivolumab and ipilimumab with SRS is warranted.